[parser] Simply receiver handling in scopes

By adding the receiver variable to the locals we'll automatically create
a proper scope info entry. The receiver is allocated before we allocate
other locals anyway, so it'll be properly allocated.

Change-Id: Ic1d57257d26473f3a50cce27c335565bcb6e06c3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3211995Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77302}

src/ast/scopes.cc

@@ -679,6 +679,7 @@ void DeclarationScope::DeclareThis(AstValueFactory* ast_value_factory) {
       THIS_VARIABLE,
       derived_constructor ? kNeedsInitialization : kCreatedInitialized,
       kNotAssigned);
+  locals_.Add(receiver_);
 }
 
 void DeclarationScope::DeclareArguments(AstValueFactory* ast_value_factory) {

src/debug/debug-scopes.cc

@@ -817,7 +817,6 @@ bool ScopeIterator::VisitLocals(const Visitor& visitor, Mode mode,
   }
 
   for (Variable* var : *current_scope_->locals()) {
-    DCHECK(!var->is_this());
     if (ScopeInfo::VariableIsSynthetic(*var->name())) continue;
 
     int index = var->index();

src/objects/scope-info.cc

@@ -89,7 +89,6 @@ Handle<ScopeInfo> ScopeInfo::Create(IsolateT* isolate, Zone* zone, Scope* scope,
       receiver_info = VariableAllocationInfo::UNUSED;
     } else if (var->IsContextSlot()) {
       receiver_info = VariableAllocationInfo::CONTEXT;
-      context_local_count++;
     } else {
       DCHECK(var->IsParameter());
       receiver_info = VariableAllocationInfo::STACK;
@@ -308,23 +307,6 @@ Handle<ScopeInfo> ScopeInfo::Create(IsolateT* isolate, Zone* zone, Scope* scope,
         info = ParameterNumberBits::update(info, i);
         scope_info.set(info_index, Smi::FromInt(info));
       }
-
-      // TODO(verwaest): Remove this unnecessary entry.
-      if (scope->AsDeclarationScope()->has_this_declaration()) {
-        Variable* var = scope->AsDeclarationScope()->receiver();
-        if (var->location() == VariableLocation::CONTEXT) {
-          int local_index = var->index() - scope->ContextHeaderLength();
-          uint32_t info =
-              VariableModeBits::encode(var->mode()) |
-              InitFlagBit::encode(var->initialization_flag()) |
-              MaybeAssignedFlagBit::encode(var->maybe_assigned()) |
-              ParameterNumberBits::encode(ParameterNumberBits::kMax) |
-              IsStaticFlagBit::encode(var->is_static_flag());
-          scope_info.set(context_local_base + local_index, *var->name(), mode);
-          scope_info.set(context_local_info_base + local_index,
-                         Smi::FromInt(info));
-        }
-      }
     }
 
     index += 2 * context_local_count;